Theaflavin-3, 3\u27-digallate decreases human ovarian carcinoma OVCAR-3 cell-induced angiogenesis via Akt and Notch-1 pathways, not via MAPK pathways

Theaflavin-3, 3\u27-digallate (TF3) is a black tea polyphenol produced from polymerization and oxidization of the green tea ployphenols epicatechin gallate and (-)-epigallocatechin-3-gallate (EGCG) during fermentation of fresh tea leaves. TF3 has been reported to have anticancer properties. However, the effect of TF3 on tumor angiogenesis and the underlying mechanisms are not clear. In the present study, TF3 was verified to inhibit tumor angiogenesis. Compared with EGCG, TF3 was more potent. TF3 inhibited human ovarian carcinoma OVCAR-3 cell-induced angiogenesis in human umbilical vein endothelial cell model and in chick chorioallantoic membrane model. TF3 reduced tumor angiogenesis by downregulating HIF-1α and VEGF. One of the mechanisms was TF3 inactivated Akt/mTOR/p70S6K/4E-BP1 pathway and Akt/c-Myc pathway. Besides, TF3 suppressed the cleavage of Notch-1, subsequently decreased the expression of c-Myc, HIF-1α and VEGF, and finally the impaired cancer cells induced angiogenesis. Nevertheless, TF3 did not have any influence on the MAPK pathways. Taken together, these findings suggest that TF3 might serve as a potential anti-angiogenic agent for cancer treatment

Theaflavin-3,3′-Digallate Enhances the Inhibitory Effect of Cisplatin by Regulating the Copper Transporter 1 and Glutathione in Human Ovarian Cancer Cells

Ovarian cancer has the highest fatality rate among the gynecologic cancers. The side effects, high relapse rate, and drug resistance lead to low long-term survival rate (less than 40%) of patients with advanced ovarian cancer. Theaflavin-3,3′-digallate (TF3), a black tea polyphenol, showed less cytotoxicity to normal ovarian cells than ovarian cancer cells. We aimed to investigate whether TF3 could potentiate the inhibitory effect of cisplatin against human ovarian cancer cell lines. In the present study, combined treatment with TF3 and cisplatin showed a synergistic cytotoxicity against A2780/CP70 and OVCAR3 cells. Treatment with TF3 could increase the intracellular accumulation of platinum (Pt) and DNA-Pt adducts and enhanced DNA damage induced by cisplatin in both cells. Treatment with TF3 decreased the glutathione (GSH) levels and upregulated the protein levels of the copper transporter 1 (CTR1) in both cells, which led to the enhanced sensitivity of both ovarian cancer cells to cisplatin. The results imply that TF3 might be used as an adjuvant to potentiate the inhibitory effect of cisplatin against advanced ovarian cancer

Theaflavin-3, 3\u27-digallate induces apoptosis and G2 cell cycle arrest through the Akt/MDM2/p53 pathway in cisplatin-resistant ovarian cancer A2780/CP70 cells

Ovarian cancer is the most lethal gynecological cancer among women worldwide. Adverse side effects and acquired resistance to conventional platinum based chemotherapy are major impediments in ovarian cancer treatment, and drive the development of more selective anticancer drugs that target cancer-specific defects. In this study, theaflavin-3, 3\u27-digallate (TF3), the major theaflavin monomer in black tea, exhibited a potent growth inhibitory effect on the cisplatinresistant ovarian cancer A2780/CP70 cells (IC50, 23.81 μM), and was less cytotoxic to a normal ovarian IOSE‑364 cells (IC50, 59.58 μM) than to the cancer cells. Flow cytometry analysis indicated that TF3 induced preferential apoptosis and G2 cell cycle arrest in A2780/CP70 cells with respect to IOSE‑364 cells. TF3 induced apoptosis through both the intrinsic and extrinsic apoptotic pathways, and caused G2 cell cycle arrest via cyclin B1 in A2780/CP70 cells. The p53 protein played an important role in TF3-induced apoptosis and G2 cell cycle arrest. TF3 might upregulate the p53 expression via the Akt/MDM2 pathway. Our findings help elucidate the mechanisms by which TF3 may contribute to the prevention and treatment of platinum-resistant ovarian cancer

Theaflavin-3, 3\u27-digallate induces apoptosis and G2 cell cycle arrest through the Akt/MDM2/p53 pathway in cisplatin-resistant ovarian cancer A2780/CP70 cells

Ovarian cancer is the most lethal gynecological cancer among women worldwide. Adverse side effects and acquired resistance to conventional platinum based chemotherapy are major impediments in ovarian cancer treatment, and drive the development of more selective anticancer drugs that target cancer-specific defects. In this study, theaflavin-3, 3\u27-digallate (TF3), the major theaflavin monomer in black tea, exhibited a potent growth inhibitory effect on the cisplatinresistant ovarian cancer A2780/CP70 cells (IC50, 23.81 μM), and was less cytotoxic to a normal ovarian IOSE‑364 cells (IC50, 59.58 μM) than to the cancer cells. Flow cytometry analysis indicated that TF3 induced preferential apoptosis and G2 cell cycle arrest in A2780/CP70 cells with respect to IOSE‑364 cells. TF3 induced apoptosis through both the intrinsic and extrinsic apoptotic pathways, and caused G2 cell cycle arrest via cyclin B1 in A2780/CP70 cells. The p53 protein played an important role in TF3-induced apoptosis and G2 cell cycle arrest. TF3 might upregulate the p53 expression via the Akt/MDM2 pathway. Our findings help elucidate the mechanisms by which TF3 may contribute to the prevention and treatment of platinum-resistant ovarian cancer

Synergistic effect of black tea polyphenol, theaflavin-3,3\u27-digallate with cisplatin against cisplatin resistant human ovarian cancer cells

Theaflavin-3, 3’-digallate (TF3) is a phenolic compound extracted from black tea. We previously demonstrated that TF3 selectively inhibited ovarian cancer cells. Ovarian cancer has high death rate because of acquired cisplatin resistance. We aimed to investigate the synergistic effect of TF3 and cisplatin (CDDP) against cisplatin resistant ovarian cancer cells. In the present study, combination treatment with TF3 and CDDP showed a synergistic cytotoxic effect in A2780/CP70 and OVCAR3 cells. Combination treatment showed a synergistic pro-apoptotic effect and synergistically induced G1/S phase cell cycle arrest. Synergistic apoptosis was accompanied by regulating protein expression of cleaved caspase 3/7, cytochrome c, Bax and Bcl-2. Combination treatment induced G1/S phase cell cycle arrest via regulating protein expression of cyclin A2, cyclin D1, cyclin E1 and CDK2/4. Combination treatment could synergistically down-regulate Akt phosphorylation in both cell lines. TF3 may be used as an adjuvant for the treatment of advanced ovarian cancer

Standardized Saponin Extract from Baiye No.1 Tea (Camellia sinensis) Flowers Induced S Phase Cell Cycle Arrest and Apoptosis via AKT-MDM2-p53 Signaling Pathway in Ovarian Cancer Cells

Ovarian cancer is considered to be one of the most serious malignant tumors in women. Natural compounds have been considered as important sources in the search for new anti-cancer agents. Saponins are characteristic components of tea (Camellia sinensis) flower and have various biological activities, including anti-tumor effects. In this study, a high purity standardized saponin extract, namely Baiye No.1 tea flower saponin (BTFS), which contained Floratheasaponin A and Floratheasaponin D, were isolated from tea (Camellia sinensis cv. Baiye 1) flowers by macroporous resin and preparative liquid chromatography. Then, the component and purity were detected by UPLC-Q-TOF/MS/MS. This high purity BTFS inhibited the proliferation of A2780/CP70 cancer cells dose-dependently, which is evidenced by the inhibition of cell viability, reduction of colony formation ability, and suppression of PCNA protein expression. Further research found BTFS induced S phase cell cycle arrest by up-regulating p21 proteins expression and down-regulating Cyclin A2, CDK2, and Cdc25A protein expression. Furthermore, BTFS caused DNA damage and activated the ATM-Chk2 signaling pathway to block cell cycle progression. Moreover, BTFS trigged both extrinsic and intrinsic apoptosis—BTFS up-regulated the expression of death receptor pathway-related proteins DR5, Fas, and FADD and increased the ratio of pro-apoptotic/anti-apoptotic proteins of the Bcl-2 family. BTFS-induced apoptosis seems to be related to the AKT-MDM2-p53 signaling pathway. In summary, our results demonstrate that BTFS has the potential to be used as a nutraceutical for the prevention and treatment of ovarian cancer

Mechanisms of Body Weight Reduction by Black Tea Polyphenols

Obesity is one of the most common nutritional diseases worldwide. This disease causes health problems, such as dyslipidemia, hyperglycemia, hypertension and inflammation. There are drugs used to inhibit obesity. However, they have serious side effects outweighing their beneficial effects. Black tea, commonly referred to as “fermented tea”, has shown a positive effect on reducing body weight in animal models. Black tea polyphenols are the major components in black tea which reduce body weight. Black tea polyphenols are more effective than green tea polyphenols. Black tea polyphenols exert a positive effect on inhibiting obesity involving in two major mechanisms: (i) inhibiting lipid and saccharide digestion, absorption and intake, thus reducing calorie intake; and (ii) promoting lipid metabolism by activating AMP-activated protein kinase to attenuate lipogenesis and enhance lipolysis, and decreasing lipid accumulation by inhibiting the differentiation and proliferation of preadipocytes; (iii) blocking the pathological processes of obesity and comorbidities of obesity by reducing oxidative stress. Epidemiological studies of the health relevance between anti-obesity and black tea polyphenols consumption remain to be further investigated

Theaflavin-3,3′-Digallate Suppresses Human Ovarian Carcinoma OVCAR-3 Cells by Regulating the Checkpoint Kinase 2 and p27 kip1 Pathways

Theaflavin-3,3′-digallate (TF3) is a unique polyphenol in black tea. Epidemiological studies have proved that black tea consumption decreases the incidence rate of ovarian cancer. Our former research demonstrated that TF3 inhibited human ovarian cancer cells. Nevertheless, the roles of checkpoint kinase 2 (Chk2) and p27 kip1 (p27) in TF3-mediated inhibition of human ovarian cancer cells have not yet been investigated. In the current study, TF3 enhanced the phosphorylation of Chk2 to modulate the ratio of pro/anti-apoptotic Bcl-2 family proteins to initiate intrinsic apoptosis in a p53-independent manner and increased the expression of death receptors to activate extrinsic apoptosis in OVCAR-3 human ovarian carcinoma cells. In addition, TF3 up-regulated the expression of p27 to induce G0/G1 cell cycle arrest in OVCAR-3 cells. Our study indicated that Chk2 and p27 were vital anticancer targets of TF3 and provided more evidence that TF3 might be a potent agent to be applied as adjuvant treatment for ovarian cancer

Inhibitory Effects of the Four Main Theaflavin Derivatives Found in Black Tea on Ovarian Cancer Cells

BACKGROUND: Some polyphenols induce apoptosis and inhibit angiogenesis. Consumption of black tea, rich in polyphenols, has been found to reduce ovarian cancer risk. Theaflavin (TF1), theaflavin-3-gallate (TF2a), theaflavin-3\u27-gallate (TF2b) and theaflavin-3, 3\u27-digallate (TF3) are four main theaflavin derivatives found in black tea. MATERIALS AND METHODS: Cell proliferation assay, Hoechst 33342 staining assay, Caspase-Glo Assay, western blot, human umbilical vein endothelial cell tube formation assay and vascular endothelial growth factor (VEGF) enzyme-linked immunosorbent assay were performed. RESULTS: All four theaflavin derivatives reduced viability of ovarian cancer cells at lower concentrations than with normal ovarian cells. TF1 mainly mediated apoptosis via the intrinsic pathway, while the others via the intrinsic and extrinsic pathways. TF1 inhibited tube formation via reducing VEGF secretion in a hypoxia-inducible factor 1α-independent manner, while the others in a HIF1α-dependent way. CONCLUSION: All four theaflavin derivatives inhibited ovarian cancer cells. Some of the effects and mechanisms of TF1 are different from those of the other three theaflavin derivatives

Saponins Extracted from Tea (Camellia Sinensis) Flowers Induces Autophagy in Ovarian Cancer Cells

Tea flower saponins (TFS) possess effective anticancer properties. The diversity and complexity of TFS increases the difficulty of their extraction and purification from tea flowers. Here, multiple methods including solvent extraction, microporous resin separation and preparative HPLC separation were used to obtain TFS with a yield of 0.34%. Furthermore, we revealed that TFS induced autophagy—as evidenced by an increase in MDC-positive cell populations and mCherry-LC3B-labeled autolysosomes and an upregulation of LC3II protein levels. 3-MA reversed the decrease in cell viability induced by TFS, showing that TFS induced autophagic cell death. TFS-induced autophagy was not dependent on the Akt/mTOR/p70S6K signaling pathway. TFS-induced autophagy in OVCAR-3 cells was accompanied by ERK pathway activation and reactive oxygen species (ROS) generation. This paper is the first report of TFS-mediated autophagy of ovarian cancer cells. These results provide new insights for future studies of the anti-cancer effects of TFS